package day190612;

import java.util.Arrays;

/**
 * @author LI DUO
 * @version 1.0
 * @date 2019/6/12 下午 05:00
 * <p>
 * 4. 寻找两个有序数组的中位数
 */
public class FindMedianSortedArrays {
    public double findMedianSortedArrays2(int[] nums1, int[] nums2) {
        int[] all = new int[nums1.length + nums2.length];
        int i = 0;
        for (; i < nums1.length; i++) {
            all[i] = nums1[i];
        }
        for (int j = 0; j < nums2.length; i++, j++) {
            all[i] = nums2[j];
        }
        Arrays.sort(all);
        if (all.length % 2 == 0) {
            return (all[all.length / 2] + all[all.length / 2 - 1]) / 2.0;
        } else {
            return all[all.length / 2];
        }
    }

    public double findMedianSortedArrays(int[] A, int[] B) {
        int m = A.length;
        int n = B.length;
        // to ensure m<=n
        if (m > n) {
            int[] temp = A;
            A = B;
            B = temp;
            int tmp = m;
            m = n;
            n = tmp;
        }
        int iMin = 0, iMax = m, halfLen = (m + n + 1) / 2;
        while (iMin <= iMax) {
            int i = (iMin + iMax) / 2;
            int j = halfLen - i;
            if (i < iMax && B[j - 1] > A[i]) {
                // i is too small
                iMin = i + 1;
            } else if (i > iMin && A[i - 1] > B[j]) {
                // i is too big
                iMax = i - 1;
            }
            // i is perfect
            else {
                int maxLeft = 0;
                if (i == 0) {
                    maxLeft = B[j - 1];
                } else if (j == 0) {
                    maxLeft = A[i - 1];
                } else {
                    maxLeft = Math.max(A[i - 1], B[j - 1]);
                }
                if ((m + n) % 2 == 1) {
                    return maxLeft;
                }

                int minRight = 0;
                if (i == m) {
                    minRight = B[j];
                } else if (j == n) {
                    minRight = A[i];
                } else {
                    minRight = Math.min(B[j], A[i]);
                }

                return (maxLeft + minRight) / 2.0;
            }
        }
        return 0.0;
    }

    public static void main(String[] args) {
        FindMedianSortedArrays sortedArrays = new FindMedianSortedArrays();
        int[] num1 = {1, 2};
        int[] num2 = {3, 4};
        System.out.println(sortedArrays.findMedianSortedArrays(num1, num2));
    }
}
